I, uh, hate to admit this but I thought I had a meter issue with my QL17 GIII when I first got it, but it turned out I had the battery in upside down. It looked right - I swear...
Jon Goodman, the Interslice seal-kit guy on eBay and elsewhere, sells a clever battery adapter called the TriDot that converts a 675 hearing aid battery to fit the QL17 GIII. The 675 batteries are zinc-oxide so they don't have a long life (couple months, maybe) after installation, but at a buck apiece, I usually just throw in a new one for my occasional use of the Canonet.